[drive surgeon]

was told my crank shaft has nearly gone on my 13 hp engine,  a new engine is nearly 800 quid 

what can be done?  it is the key thing that has worn on the crank shaft.

might need another machine asap 

[Nathanael Jones]

You can get cheap 13hp engines off ebay that are compatible, just swap them straight over. Not sure if its a false economy but Loncin are a well known engine maker.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=350174800312

[jonnyald]

if it IS  just the key on the crank thats broken, simply buy a new one or even make one up .i did this once,wasnt hard, took about 1 hour to make a new key



for your key to have messed up means the nut on the end of the crankshaft must have worked loose. be sure you fix this nut on tightly with loctite after u have fitted the new key

[drivewasher]

I think DS means the actuall keyway milling on the crankshaft protrusion (Q type) has been mashed and is no longer good enough to drive a new key. New keys are standard stock machine steel and shouldn't be a problem obtaining.

There is no nut on the end of the crankshaft! The punp drive collar just sits over the end of the crank. The gearbox or pump flange bolts to te crankcase end plate to keep it on there. There is an identical keyslot machined in the drive collar, and a square key is slid inbetween the two. the key is locked in place just to stop it sliding about and wearing the slots by an allen grub screw in the drive collar that presses onto the key in the slots. Access to this grub screw is through a small elongated hole in the pump/gearbox "bell housing". Most fitters wrongly leave this grub screw slack as you have to line it up with the small hole to tighten it. Inthe belief that the key can't come out as it's to long, this is so but in leaving the key slack it inevitably vibrates up and down the slots wearing them bigger particulary the crankshaft slot as thats the softest material.
Unfortunatley this wear only becomes apparent long after the gaurantee period has expired. So basically it's bad assembly practice.

PIC1 shows the access hole and the hole the grub screw sits in to clamp the key

PIC2 shows the drive collar on end of pump and the route for installing the grub screw(shown by a steel rod)

[drive surgeon]

steve what would you do as the guy said it will go anytime soon altogether, i cant afford a new engine but he said the crankshaft is the whole drive of the engine/

[drivewasher]

I need to see it really. To gauge how bad it is. I bet your coupling didn't have the grub screw in or it wasn't tightened fully. I put loctite on it.

Maybe a bit of dressing with a new key, the longest that can be got in there and a new grub screw tightened properly with loctight on it.
I would possibly try coating the mating parts in bearing fit solution just as an aid in keeping it all tight.

[drive surgeon]

thanks for giving me advice steve. i dont like ringing you as i know you are a busy guy but your help is greatly appreciated and if it was not for people like you i would not learn anything so thanks.   i will have to see who the hell can get me a new crankshaft. the guy who told me it was knackered told me it would be cheaper to buy a new engine as he charges a fortune in labour cocsts plus vat and parts. 

[drive surgeon]

hi steve what do you think of these?    it seems daft tho buying a whole new engine when its just that steel crank shaft that needs replacing?

http://cgi.ebay.co.uk/HONDA-GX390-13HP-ENGINE-FULLY-RECONDITIONED-22mm-SHAFT_W0QQitemZ140329032361QQcmdZViewItemQQptZUK_BOI_FarmingEquipment_RL?hash=item20ac431aa9&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1683%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

[drivewasher]

That engine won't fit on a pump. Its only 22mm dia without a keway

[drivewasher]

Just thinking about your shaft. We could possibly weld the key oto the shaft then drss it to fit into the coupler/drive collar. This would be a last resort sort of the moon or bust exercise, as  the crank is knackered welding it will get you untill it has to be removed from the engine at a later date, but that ain't gonna happen is it?

[Nathanael Jones]

This one should fit shouldn't it? (same seller)
http://cgi.ebay.co.uk/HONDA-GX390-13HP-ENGINE-FULLY-RECONDITIONED-22mm-QSHAFT_W0QQitemZ130310738180QQcmdZViewItemQQptZUK_BOI_FarmingEquipment_RL?hash=item1e57201104&_trksid=p3911.c0.m14&_trkparms=65%3A12|66%3A2|39%3A1|72%3A1683|240%3A1318|301%3A0|293%3A1|294%3A50

[drivewasher]

Ds,
How u get on with crankshaft keyway?

[drive surgeon]

not done anyhting steve.  i just dont know what to do.  its running ok at mo but could go anytime and i have no spare machine only 5.5 hp ones. 

i aint got a spare 1400 quid either to buy new one.,  bloody dear over here these machines.  might buy from merril again!!

[drivewasher]

Do you want me to get the MIG WELDER out!  You would be better trying a repair while everything is still workig as its all still lined up now

[Joe H]

If its on its way out then getting it welded might be the best option.
Do it before it goes completely.

[drive surgeon]

can you fix it steve?  have you repaired crank shafts before? i could come early next week.

[drivewasher]

Nope never done one before, but till I try I'll never know will I?
Would be easier to do it while it still has drive rather than try lining it up when it's completley b*****xd
sorry I mean brocken!

As I see it i's the moon or bust syndrome! We have the technologie... Just